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_W_e_i_g_h_t _v_e_r_s_u_s _a_g_e _o_f _c_h_i_c_k_s _o_n _d_i_f_f_e_r_e_n_t _d_i_e_t_s
_D_e_s_c_r_i_p_t_i_o_n:
The 'ChickWeight' data frame has 578 rows and 4 columns from an
experiment on the effect of diet on early growth of chicks.
_U_s_a_g_e:
ChickWeight
_F_o_r_m_a_t:
An object of class 'c("nfnGroupedData", "nfGroupedData",
"groupedData", "data.frame")' containing the following columns:
weight a numeric vector giving the body weight of the chick (gm).
Time a numeric vector giving the number of days since birth when
the measurement was made.
Chick an ordered factor with levels '18' < ... < '48' giving a
unique identifier for the chick. The ordering of the levels
groups chicks on the same diet together and orders them
according to their final weight (lightest to heaviest) within
diet.
Diet a factor with levels 1, ..., 4 indicating which experimental
diet the chick received.
_D_e_t_a_i_l_s:
The body weights of the chicks were measured at birth and every
second day thereafter until day 20. They were also measured on
day 21. There were four groups on chicks on different protein
diets.
This dataset was originally part of package 'nlme', and that has
methods (including for '[', 'as.data.frame', 'plot' and 'print')
for its grouped-data classes.
_S_o_u_r_c_e:
Crowder, M. and Hand, D. (1990), _Analysis of Repeated Measures_,
Chapman and Hall (example 5.3)
Hand, D. and Crowder, M. (1996), _Practical Longitudinal Data
Analysis_, Chapman and Hall (table A.2)
Pinheiro, J. C. and Bates, D. M. (2000) _Mixed-effects Models in S
and S-PLUS_, Springer.
_S_e_e _A_l_s_o:
'SSlogis' for models fitted to this dataset.
_E_x_a_m_p_l_e_s:
require(graphics)
coplot(weight ~ Time | Chick, data = ChickWeight,
type = "b", show.given = FALSE)
